This question is very good
Plasma membrane which is also the cell membrane
In the winter its color changes to more resemble their <em>winter</em> surroundings, so they are more white, enabling them to blend in better with their white surroundings. In summer, its color changes to more resemble its <u><em /></u><em>summer</em> surroundings, so they are more brown like the rocks and ground around them.
Mycoderma aceti uses acetic fermentation to produce ATP
C2H6O+O2-->CH3COOH+H2O
Saccharomyces cerevisae uses alcoholic fermentation to produce ATP
C6H12O6-->2C2H5OH+2CO2